Source: biffbampop.com

1. Batman: Gotham by Gaslight

“…fought Jack the Ripper?”

Written by Brian Augustyn and drawn by Mike Mignola. I dare you to turn that down. You can't, because it's awesome. It's also widely considered to be the first Elseworlds story. And, as far as I'm concerned, it’s the best.

The year is 1889.  After the murder of his parents, Bruce Wayne sets off to travel the world on a journey of self discovery. After meeting with Sigmund Freud, he decides to return to Gotham. In Gotham, he sees first-hand the crime epidemic hitting the city and takes on the mantle of the Batman to fight crime.

When a series of murders start up that closely resemble the Jack the Ripper murders and Bruce Wayne is framed, he takes to the streets to clear his name and catch the true culprit. The art and visual design of Gaslight is goshdarn beautiful. I mean, Mignola art is always beautiful, but Mignola drawing Victorian era Batman is maybe the most perfect thing of all time.

And there we go! Unfortunately, most of these stories are no longer in print, which is depressing, as they're all pretty great. But hey, if you can get your hands on one, you'll have a pretty great afternoon ahead of you.